Sub-surface well blowout preventer operated mechanically from the surface

ABSTRACT

Well flow control apparatus includes a bottom hole pumping string, a stuffing box in the well to seal off about the pumping string and carried by an inner casing string, and an outer casing string. Controlled displacement of the pumping string effects a pack-off between a plug on the pumping string and tubing suspended by the outer casing string below the inner casing string; and the inner casing string, stuffing box, pumping string, plug and bottom hole pump may all be retrieved while the well is secured against blowout.

United States Patent 1191 [11] 3,817,327 Grable et al. June 18, 1974 SUB-SURFACE WELL BLOWOUT 2,192,945 3/1940 Toney 166/226 PREVENTER OPERATED MECHANIC ALLY gnox ean FROM THE SURFACE, 3,005,413 10/1961 Coberly l66/68 X [75] Inventors: Donovan B. Grable, Long Beach; 3,313,350 4/1967 Page 166/72 X C. Laney, Torrance both of 3,376,936 4/1968 Tomlin 166/73 X Calif. Primary Examiner-George H. Krizmanich [73] Asslgnee: gigg Long Beach Attorney, Agent, or FirmWilliam W. Haefliger [221 Filed: July 17, 1972 [57] ABSTRACT Well flow control apparatus includes a bottom hole [2]] Appl' 272320 pumping string, a stuffing box in the well to seal off about the pumping string and carried by an inner cas- [52] US. Cl. 166/72, 166/226 ing string, and an outer casing string. Controlled dis- [51] Int. Cl. E2lb 33/03 placement of the pumping string effects a pack-off be- [58] Field of Search 166/72, 73, 68, 226; tween a plug on the pumping string and tubing sus- 277/73 pended by the outer casing string below the inner casing string; and the inner casing string, stuffing box, [56] References Cited pumping string, plug and bottom hole pump may all UNITED STATES PATENTS be retrieved while the well is secured against blowout.

1,182,083 5/1916 Fording 166/73 X 8 Claims, 5 Drawing Figures W111 2;. @8 X 50 2 I2 1 I a g? g j PATENTEBJUR 18 I974 SHEET 1 OF 2 Z I f m3 7 5x3; 55%.

SUB-SURFACE WELL BLOWOUT PREVENTER OPERATED MECHANICALLY FROM THE I SURFACE BACKGROUND OF THE INVENTION This invention relates generally to the control of production fluid flow from and within wells; and more particularly concerns apparatus and methods for controlling the flow of well production fluid to the well head.

There is a need for simple and effective means to achieve shut-off of production flow in a pumped well in a very simple manner and also to provide down-hole blow out prevention protection while the well is being pumped. No prior system apparatus or methods of which we are aware satisfy the above need in the unusually advantageous manner now afforded by the present invention wherein these objectives are met as incidents to the pumping operation itself. There is also a need to simplify the locating underground of a stuffing box for the pumping rod string.

SUMMARY OF THE INVENTION It is a major object of the invention to satisfy the above needs, and to provide a well flow control system incorporating unusual advantages in construction, mode of operation and results, as will be seen.

Basically, the invention is embodied in control apparatus comprising first tubular means (which may for example include outer casing supporting production tubing) in the well carrying an internal seat; an elongated cylindrical string such as a rod string extending within the tubular means to be vertically movable from the wellhead relative to the tubular means; and a flow controlling plug carried on the rod string to be moved vertically between a first position spaced from the seat and in which well production fluid flows past the plug, and a second position in which the plug engages the seat for blocking upward flow of production fluid. As will be seen, under normal conditions the plug moving with the rod string may be kept spaced from the seat, as for example during up and down stroking of the rod string operating a bottom hole pump, however if a blowout is to be prevented, the plug may be immediately displaced by the rod string out of its normal stroking range within an enlarged tube formed cavity to seat the plug. The seat may be a downwardly presented upper seat, or an upwardly presented lower seat, or both may be utilized as will be seen.

It is another object of the invention to provide second tubular means such as inner casing suspended with clearance within the first or outer casing and carrying rod sealing means (as may include a sub-surface stuffing box) near the lower terminal of the second casing to seal off against the latter and also to seal off about the rod string during its stroking. As a result, the production fluid is caused to flow to the well head between the inner and outer casings, the rod string is centered within the inner casing so as not to frictionally rub against the latter, the stuffing box is located below the well head so as to reduce the overall height of the surface equipment, and the rod string may float laterally with the lower terminal of the inner casing, within limits imposed by the inner diameter of the outer casing.

It is still another object of the invention to provide surface equipment accommodating the casing and rod strings as described, and so as to facilitate their running into and out of the well. As will be seen, a ring may carry and extend about the uppermost extent of the inner casing which projects above the spool suspended upper end of the outer casing, thereby to define a flow receiving annulus receiving flow from between the inner and outer casings, and from which production fluid may be passed to exterior flow lines. The ring may be supported by a flange, and flow may be directed laterally through the latter in a modified form of the invention. Also, a surface blowout preventer may be provided above the flange and sized for passing the rod string, and that preventer can be installed or removed while the rod manipulated sub-surface preventer is closed, as will be seen.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which:

DRAWING DESCRIPTION FIG. 1 is a vertical elevation showing a well installation incorporating the invention;

FIG. 2 is an enlarged vertical section taken on lines 22 of FIG. 1;

FIG. 3a and 3b are enlarged vertical sections showing well head and sub-surface details; and

FIG. 4 is a vertical section showing a modified well head installation.

DETAILED DESCRIPTION In accordance with the invention and as seen in FIGS. 1 and 2, well flow control apparatus includes first tubular means, as for example outer casing 26, in a well 11 (which may be cased at 10) and an internal seat thereon below the well head 12 in cellar 12a. For example, the seat may take the form of the downwardly presented upper valve seat 13, better seen in FIG. 2 as formed by upwardly tapered adapter section 140 of tubing 14; or, the seat may take the form of an upwardly presented lower valve seat 15 formed by downwardly tapered adapter section 14b of tubing 14. The seat or seats may be part of the tubing or separate seat structures carried thereby. The main extent of the tubing may have larger inner and outer diameter dimensions than those of the tubing sections 16 connected in end-to-end relation therewith, for unusually advantageous purposes as will appear. Characteristically, both seats 13 and 15 will be provided, for production flow control purposes to be described. Connectors are provided at and 81.

An elongated cylindrical string, as for example rod string 17, extends within the tubing to be vertically movable from the well head relative to the tubing. A plug 18 is carried by the rod string 17 to be moved between a first position or positions spaced from either seat (in which event well fluid flows upwardly within tubing 14 past the plug, as for example around the plug as indicated by arrows l9), and a second position in which the plug engages the seat for blocking such upward flow of well fluid. For example, the plug may be reciprocated in cavity 25 by the rod string 17, as during normal well pumping between upper and lower positions indicated at 18a and 18b in FIG. 1 respectively spaced from positions of engagement with either of the seats 13 and 15, the rod stroke length or range indicated at 20. Well production fluid flows upwardly through tubing 14 during such stroking, the latter displacing a bottom hole sub-surface pump or swab 21 up and down in the bottom hole tubing. Means at the top of the well to reciprocate the rod string is generally indicated at 22, and may take the form of the counterbalancing drive means disclosed in either of U.S. Pat. Nos. 3,516,762 and 3,521,445 or in pending Grable application WELL PUMPING CONTROL Ser. No. 262,605 filed June 14, 1972. The broking lines 18c and 18d in FIG. 2 indicate alternative secondary positions of plug engagement with the seats 13 and 15, and in either of which upward flow of well fluid is blocked, for example to prevent well blowout. For this purpose, the plug may incorporate a body supported annular elastomer lip 22 adapted to flex outwardly as at 22a to seal against the inner wall of tube 14 when the plug is in either sealing position 18c and 18d. Displacement of the plug to either of the latter positions may be quickly effected by manipulation of the rod string from the surface; thus if the string is moving up it may be lifted until the plug seats, and if the string is moving down, it may be lowered until the plug seats. Positions 18a and 18b may be less than 2 feet from seating positions as described.

Referring to FIGS. 3a and 3b, the first tubular means such as outer casing 26 is shown to have a reduced diameter lowermost portion 260 supporting production tubing 16 as via connector sleeve 27. Casing 26 is suspended at the well head as by thread connection at 28 with a carrier in the form of an annular spool piece 29, the latter received in and supported by tubular body member 30. Note that O-ring seals 31 seal off between the bore of member 30 and the spool piece outer diameter.

Second tubular means, as for example inner casing 32, extends within the outer casing 26 and in spaced relation thereto to form therewith an annulus 33 conducting production fluid upwardly to the well head. Sealing means is carried by the casing 32, as for example at the lower terminal of the latter, to pass and seal off about the rod string 17 above the plug 18 and also to seal off against the casing 32. Such sealing means may typically include an annular plug 34 peripherally attached to the casing 32 and forming a central threaded bore 34a removably receiving a threaded pin 35a of a stuffing box 35 passing the rod string. One important advantage of this construction lies in the fact that the stuffing box may float laterally with the lower terminal of casing 32, but as limited by engagement with the bore of casing 26, in response to lateral movement of the rod string during its up and down stroking, so as not to bind or inhibit such stroking. In addition, casing 26 may float laterally in the well annulus 90.

Inner or second casing 32 has upper extent 32a projecting upwardly through the outer or first casing at the well head, and annular structure extends about said upper extent 32a to form a well production flow receiving annulus 37 in direct communication with the annular space 33 between casings 26 and 32. Such annular structure may include a flange spool 38 removably supporting the second or inner casing as by thread connection at 39 to a ring 40. The latter is shown as attached at 41 to the top of casing 32 upper extent 32a, and also 6 forms an upper continuation of annular space 37. From the latter production fluid may flow to surface lines via flow, nipples 43. Flange 38 may be supported by top flange 30a of body member 30, an O-ring seal 44 sealing off therebetween.

FIG. 4 shows a surface blowout preventer 45 at the top of the stack 46 which remains the same as described in FIG. 3a, excepting that the top flange 47 conducts production fluid laterally to line via port 48 and from the annular space 37. In this form, flange 47 supports the inner casing 32 at 49, and also supports the blowout preventer 45 which may have the construction as described in US. Pat. No. 2,609,836 to Knox. Accordingly, the invention permits running of the rod string vertically through the preventer while the latter is semi-closed. This type of preventer affords clearance to run any size tools, tubing or rods through the inside diameter in the preventer.

During installation, with the preventer 45 removed, or as seen in FIGS. 3a and 3b, tubing 14 and 16 and the outer casing 26 is first installed and landed; thereafter, the inner casing 32 is installed within the outer casing, and landed; next, the rod string with attached bottom hole pump is run into the well, plug 18 on that string passing through the threaded bore 34a and forcibly through the tubing 16 in slightly radially compressed condition. The stuffing box is landed at bore 34a and the threaded connection made up. Finally, the rod string is reciprocated up and down as previously described to elevate well fluid to the well head via the clearance between the first and second string.

The invention also contemplates retrieval from the well of the rod string 17, pump 21, stuffing box 35 and inner casing string 32, while maintaining the well secure against blowout. In this regard, and referring to FIG. 2, the rod string may first be elevated to seat the plug 18 and 13 or to displace the plug into the tubing bore 16a. Thereafter, and as seen in FIGS. 3a and 3b, the inner casing string may be elevated along with the rod string to permit successive retrieval of the string sections along with the stuffing box, at the well head, the plug 18 simultaneously maintaining a pack-off against the reduced bore 16a of the tubing string through which the plug is drawn upwardly, to secure the well.

In addition, and after retrieval of the stuffing box, but before release of the sub-surface pack-off, a surface pack off device 190, such as a rod stripper (similar to the preventer 45) may be installed at the well head, as on flange 30a, and the remainder of the rod string together with the plug 35 and pump 21 may be retrieved upwardly through that device. Accordingly, a surface pack-off may be maintained, for well security against blowout, during the final phases of rod string and bottom hole pump retrieval. This is of advantage where the sub-surface pack-off is interrupted, as for example will occur in FIG. 1 when the plug 18 enters the enlarged bore regions 26a defined by the outer casing 26. Accordingly, the well is completely secure against blowout during all phases of retrieval of the rod string and pump, and there is no need to bleed off well pressure in the tubing before installation of the rod stripper, the well pressure being contained at all times.

We claim:

1. Well flow control apparatus, comprising a. first tubular means in the well, and a downwardly presented upper seat on said means below the well head,

b. a rod string extending within the tubular means and having a range of vertical reciprocation to operate a well pump for pumping well fluid upwardly through said means,

c. a plug carried on the rod string to be reciprocated within said tubular means in'spaced relation to said seat as the rod reciprocates within said range while well fluid flows upwardly within said tubular means past the plug,

d. the plug sized to engage the upper seat and block said upward flow in response to upward displacement of the rod string beyond the upper limit of said range, and

e. second tubular means extending within the first tubular means and sealing means carried by said sec- 0nd tubular means to pass and seal off about the rod string above said plug, and to seal off against the second tubular means, therebeing clearance between the first and second tubular means to pass the upward flow.

2. The apparatus of claim 1 including support means at the well head suspending said first tubular means in the well for upward removal therefrom.

3. The apparatus of claim 2 including blowout prevention means at the well head and having a closable aperture passing said rod string and sized to pass said plug and said first tubular means.

4. The apparatus of claim 1 wherein said first tubular means has a vertically elongated portion which is diametrically enlarged to form a cavity within which the plug is reciprocable vertically with flow passing clearance at the side of the plug.

5. The apparatus of claim 1 including an upwardly presented lower seat on the first tubular means and sufficiently below the upper seat as to normally remain out of engagement with the plug as the rod string reciprocates within said range, the plug sized to engage the lower seat and block vertical flow therethrough in response to downward displacement of the string below the lower limit of said range.

6. The apparatus of claim 1 wherein said sealing means is carried near the lower terminal of the second tubular means which is free to float laterally within the confines of the first tubular means to accommodate lateral movement of the rod string.

7. The apparatus of claim 6 wherein the second tubular means has upper extent projecting upwardly through the first tubular means at the well head, and annular structure at the well head extending about said upper extent of the second tubular means to form a flow receiving annulus, the rod string projecting upwardly through the second tubular means at the well head.

8. The apparatus of claim 7 wherein said annular structure removably supports said second tubular means for upward removal therefrom.

I UNITED STATES PATENT OFFICE A CERTIFICATE OF CORRECTION June 18, 197

Patent No. 8 Dated Inventor) Dbnovan B. Grable and Bill 0. Laney It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

On summary page after [751 "Assignee: Hydro-Combo, Inc Long Beach, Calif." should be deleted.

Signed and sealed this 4th day of February 1975.

(SEAL) Attest:

MCCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. Well flow control apparatus, comprising a. first tubular means in the well, and a downwardly presented upper seat on said means below the well head, b. a rod string extending within the tubular means and having a range of vertical reciprocation to operate a well pump for pumping well fluid upwardly through said means, c. a plug carried on the rod string to be reciprocated within said tubular means in spaced relation to said seat as the rod reciprocates within said range while well fluid flows upwardly within said tubular means past the plug, d. the plug sized to engage the upper seat and block said upward flow in response to upward displacement of the rod string beyond the upper limit of said range, and e. second tubular means extending within the first tubular means and sealing means carried by said second tubular means to pass and seal off about the rod string above said plug, and to seal off against the second tubular means, therebeing clearance between the first and second tubular means to pass the upward flow.
 2. The apparatus of claim 1 including support means at the well head suspending said first tubular means in the well for upward removal therefrom.
 3. The apparatus of claim 2 including blowout prevention means at the well head and having a closable aperture passing said rod string and sized to pass said plug and said first tubular means.
 4. The apparatus of claim 1 wherein said first tubular means has a vertically elOngated portion which is diametrically enlarged to form a cavity within which the plug is reciprocable vertically with flow passing clearance at the side of the plug.
 5. The apparatus of claim 1 including an upwardly presented lower seat on the first tubular means and sufficiently below the upper seat as to normally remain out of engagement with the plug as the rod string reciprocates within said range, the plug sized to engage the lower seat and block vertical flow therethrough in response to downward displacement of the string below the lower limit of said range.
 6. The apparatus of claim 1 wherein said sealing means is carried near the lower terminal of the second tubular means which is free to float laterally within the confines of the first tubular means to accommodate lateral movement of the rod string.
 7. The apparatus of claim 6 wherein the second tubular means has upper extent projecting upwardly through the first tubular means at the well head, and annular structure at the well head extending about said upper extent of the second tubular means to form a flow receiving annulus, the rod string projecting upwardly through the second tubular means at the well head.
 8. The apparatus of claim 7 wherein said annular structure removably supports said second tubular means for upward removal therefrom. 